Vivaria house a number of animals, typically test animals such as mice, in a number of cages, often a large number. The test animals are frequently used to test drugs, genetics, animal strains, husbandry experiments, methods of treatment, procedures, diagnostics, and the like. We refer to all such uses of a vivarium as a study. The animals in a vivarium must be observed, either manually by humans or by automated means, such as by the use of video cameras. Of critical importance in a study is correct identification of the animals.
Rodents may be marked by tattooing their tails with symbols, such as digits, a bar code, a vine code or other symbols. Animals may have a mark placed on the animal by many other methods, such as marking toes, placement of ear tags or ear notches. The markings on the animals may not be well formed or consistently formed. In some cases marking may be partially or wholly natural on the animal, such as spots.
The challenge in automatic identification of such marked animals is that the initial markings are thus arbitrary, and addition, degrade over time, often significantly, over time. They fade, bleed, stretch due to growth, distort, become damaged, get covered by temporary detritus, and degrade from other causes.
Prior art suffers from both an inability to reliably read arbitrary markings and to reliably read markings that change over time.